Toothbrushes of varying shapes and sizes are known for cleaning teeth and dental prosthesis. Typically, a toothbrush includes a rectangular or oval head, a handle, and a neck connecting the handle to the head. The head includes an array of bristles that are ultimately responsible for removing plague and foreign matter from the teeth during brushing. The head (less the bristles), neck, and handle are typically formed as a unitary device through a molding process.
Most often, the head connects to the neck and the neck connects to the handle such that the resulting head, neck, and handle combination are in a relatively straight line along their longitudinal axes. However, in some other embodiments, such as those illustrated in U.S. Design Pat. Nos. 44,997; 47,669; 73,245; 77,115; 175,894; 259,977; and 282,603, the neck and head are oriented perpendicular to each other in the shape of a"T." The handle is typically straight, relatively long and rigid, but in some toothbrush embodiments the handle includes bends or angles either to make the handle more comfortable for a user to hold and/or to improve the toothbrush user's ability to access hard-to-reach surfaces of the teeth.
Toothbrushes of the types described above are effective for cleaning most areas of the teeth or dental prosthesis, but they also have specific limitations. These limitations stem mainly from the fact that bristles, by their nature, clean most effectively when they extend substantially perpendicular to the surface being cleaned. Given the positioning and motion constraints that are present when using devices having long, straight, rigid handles within the confines of the human mouth, a user cannot readily position the bristles of prior art toothbrushes so that maximally effective cleaning can be realized over all areas of the teeth, dental work and gums, especially those areas that are on the lingual, or tongue, side of the teeth. These disadvantages have been ameliorated somewhat by various improvements directed toward improving the maneuverability of toothbrush heads, such as making the head smaller, angling the brush handle and/or the head, providing a flexible joint in the handle and arranging bristles of varying lengths to form tufts having special contours intended to improve their penetration of irregularly shaped structures. Some examples of these improvements are described in U.S. Pat. Nos. 4,463,470; 4,800,608; 5,613,262; and 5,628,082.
However, such improvements are not entirely sufficient to effectively enable cleaning of all areas of the teeth, particularly those areas on the lingual side of the teeth and between teeth. For example, typical prior art toothbrush heads include an array of bristles that extend from a flat surface lying along a single plane that is perpendicular to the longitudinal axis of the bristles. By contrast, the lingual side of the teeth defines a convex curvature. This convex curvature is particularly pronounced at the front, or anterior, portion of the mouth. Therefore, due to such geometric incompatibility, toothbrush heads cannot effectively clean all lingual side anterior tooth surfaces no matter which configuration the neck and head are in (i.e., either straight or T-shaped). In addition, the straight nature of the necks of most toothbrushes makes maneuvering the toothbrush head difficult on the back (i.e., lingual) side of the teeth because the neck bumps into the teeth, deflecting the head of the brush away from proper contact with the lingual surface of the teeth.
To overcome the shortcomings of prior art toothbrush configurations, toothbrush users tend to engage the bristles more forcefully on the lingual surfaces of the teeth in an attempt to more effectively clean the lingual tooth surfaces. However, brushing more forcefully does not necessarily result in cleaner teeth. Bristles clean most effectively when their tips engage the surface being cleaned under a force that lies within a particular range of forces related to the stiffness of the bristles. If the force is not great enough, the bristle tips will not engage the surface being cleaned with sufficient pressure to do an effective a job of cleaning. On the other hand, if the force is too great, the bristles will bend or flatten so as to engage the surface being cleaned with their sides rather than their tips, also resulting in less than optimal cleaning. In addition, depending on the angle of engagement between the bristles and the teeth and the force applied, flattening of some bristles may result in flattening of other bristles due to the proximity of all the bristles on the toothbrush head. For example, when one brushes the lingual side of his or her posterior, or back, teeth, he or she typically angles the toothbrush in an attempt to avoid the anterior teeth and almost inevitably engages the lingual tooth surfaces first with the tips of the bristles at the front end of the toothbrush head. As the force applied to the bristles is increased, the front bristles bend toward the rear of the toothbrush head contacting neighboring bristles and causing the neighboring bristles to likewise bend rearwardly. This domino effect continues affecting all the bristles in such a manner that the bristles engage the tooth surfaces on their sides instead of at their tips. Such side engagement repeats as the person moves the toothbrush head back-and-forth in his or her mouth. As noted above, engaging the tooth surfaces with the sides of the bristles results in less than optimal cleaning.
The above shortcomings of prior art toothbrushes also extend to cleaning between teeth. Bristles clean between teeth most effectively when their tips project between the teeth. However, due to the flat shape of the toothbrush head and the geometry of the toothbrush neck, cleaning between teeth, particularly from the lingual side of the teeth, is difficult. Consequently, toothbrush users typically apply excessive force to the bristles in an attempt to force the tips of the bristles into the spaces between the teeth. Application of excessive force typically results in the tips of the bristles deflecting away from the surface intended to be cleaned and less efficient cleaning occurs.
Therefore, a need exists for a toothbrush and method of fabricating the same that facilitate effective cleaning of the lingual side of the teeth and between teeth, and that permit toothbrush users to have enough confidence when brushing to apply only the appropriate amount of force related to the stiffness of the bristles of their toothbrushes, thereby avoiding excessive force that results in less than optimal cleaning.